ErxYb(3-x)Q9 (1, x = 1, 2), NdYb2Q9 (2), NdEr2Q9 (3) and NdErYbQ9 (4), have been obtained through a simple molecular strategy, by controlling reactant stoichiometry. In 2-4, the templating effect of the molecular framework allows to control the metal distribution across the coordination sites where the central position is occupied by the larger Nd ion and the terminal ones by the almost vicariants Yb3+ and Er3+, drastically reducing molecular speciation. Remarkably, 4 represents the first example of a discrete molecular entity containing three different Ln ions simultaneously emitting in three different spectral regions in the NIR, upon single visible wavelength excitation. Highly transparent and homogeneous doped silica glasses have been prepared, which show the same optical properties of the incorporated complex in solution.

Pulsed metal organic chemical vapor deposition (PMOCVD) was used to grow high Mgcontent, high quality, wurtzite MgxZn1-xO (MgZnO)epitaxial film to realize photodetectors and emitters in the solar blindspectral window. MgZnO films with various Mg contents were deposited on c-planeAl2O3 with and without AlN buffer layer. The band gapof the films range from 3.24 eV to 4.49 eV, corresponding to fraction of Mgbetween x=0.0 to x=0.51, asdetermined by Rutherford backscattering spectroscopy (RBS). Cathodoluminescence(CL) measurement showed a linear blue shift in the spectral peak position ofMgxZn1-xO with an increase in x. Nomulti-absorption edge or CL band splitting was observed, indicating the phasepurity of the films and was confirmed by XRD analysis. The surface quality ofthe films has improved with the increase in Mg content. To the best of ourknowledge, the current result shows the highest Mg content(x=0.51), high quality, single phase wurtzite MgZnOepitaxial film ever grown by MOCVD. This is realized due to the non-equilibriumbehavior of PMOCVD in which radicals that are formed during the growth processwill have insufficient time to reach equilibrium.

Depsipeptide-based multiblock copolymers synthesized from dihydroxy telechelic oligodepsipeptide precursors are promising candidate materials for biomedical and pharmaceutical applications. High molecular weight polymers in polyaddition reactions e.g. of diols with diisocyanates can only be reached when reactive groups are equivalent and a high conversion for this step growth polymerization is obtained. However, in depsipeptide-based multiblock urethanes reported so far, the stoichiometric ratio of the diisocyanate compound exceeded the theoretical value of 100% by far. In order to investigate the influence of the dosing system in this unusual behavior of the stoichiometric reaction two dosing devices, a solid dosing unit (SDU) and a gravimetric dosing unit (GDU) were used for a gravimetric transfer of an oligo(3-sec-butylmorpholine-2.5-dione) (OBMD) as model oligodepsipeptide. The OBMD precursor, which was transferred as a solid or as a highly viscous solution, was reacted with an isomeric mixture of 2,2,4- and 2,4,4-trimethylhexamethylene diisocyanate (TMDI) as chain extender. Two series of 49 reactions were performed and the chain extension efficacy of the building block was compared between the SDU and GDU as well as with respect to the Carothers equation. When the GDU was used the chain extension yielded higher molecular weights, proving the high accuracy of the dosing device, and the molar ratio of TMDI required for the high-throughput synthesis of the depsipeptide-based multiblock copolymers was similar to depsipeptide-based multiblock copolymers created in a classical synthesis approach.

Carbon nanotubes (CNTs), with exceptional thermal and mechanical properties as well as inherently high surface area, are an attractive candidate for integrating into thermal structures of advanced power electronics. Growth of vertically aligned carbon nanotubes (VACNTs) directly onto copper (Cu) substrates is a promising approach to apply CNTs as novel thermal interface materials (TIMs) in electronics packaging. However, compared to growing CNTs on conventional inert substrates such as SiO2, direct growth of controllable CNT arrays onto Cu substrates is significantly more challenging due to the diffusion of metallic catalyst into the substrate during growth. By depositing an appropriate buffer layer on the Cu substrate surface, VACNTs of good alignment and high quality were reproducibly synthesized on the Cu substrate via the chemical vapor deposition (CVD) method in this study. The effect of different buffer layers on the CNT growth, nanotube structure and quality was investigated (SEM, Raman), particularly in terms of the interfacial properties between the CNT array and Cu substrate (Tensile compression force tester, Laser Flash Analysis). Our experimental results indicated that the buffer layer material, deposition method, and thickness play a key role in regulating the CNT layer growth/structure, leading to variable mechanical and thermal properties. The fundamental understanding thus obtained allows the successful synthesis of VACNT on copper substrates with desired structure and properties.

Glasses of the series (mol.%) 40 Na2O, (20-x) Al2O3, x Fe2O3, 40 P2O5 were irradiated with 8 MeV electrons to doses equivalent of 0.1, 0.5, and 1.0 MGy and characterized by FTIR spectroscopy and ESR at room temperature. FTIR spectra of all the glasses consist of strong bands due to O-P-O stretching modes in (PO4)3- and (P2O7)4- units at 1000-1200 cm-1, P-O-P stretching modes at 900-950 cm-1 (νas) and 700-750 cm-1 (νs), and bending modes in the PO4 units. The wavenumber range lower 800 cm-1 has some contribution due to stretching modes in MO4 and MO6 (M = Al, Fe) units. Moreover the bands at 3300-3700 cm-1 and 1550-1650 cm-1 due to stretching and bending modes in both absorbed and structurally bound H2O molecules were present. As irradiation dose increases the bands due to stretching and bending modes in water molecules and M-O-H bonds become stronger and are split. No essential changes with increasing dose were observed within the spectral range of stretching modes of the O-P-O and P-O-P bonds. Irradiation yields phosphorus-oxygen hole centers - PO42- (D5) and PO42- (D6), and PO32- ion-radicals (D2) observable in ESR spectra of low-Fe glasses. At x>5 their responses are overlapped with strong broad line due to Fe(III). On the whole, with the increase in iron content the glass structural evolution decrease.

The production of hydrogen by photocatalytic water splitting is a potentially clean and renewable source for hydrogen fuel. Cadmium chalcogenides are attractive photocatalysts because they have the potential to convert water into hydrogen and oxygen using photons in the visible spectrum. Cadmium sulfide rods with embedded cadmium selenide quantum dots (CdSe@CdS) are particularly attractive because of their high molar absorptivity in the UV-blue spectral region, and their energy bands can be tuned; however, two crucial drawbacks hinder the implementation of these materials in wide spread use: poor charge transfer and photochemical instability.

Utilizing photochemical deposition of co-catalysts onto CdSe@CdS substrates we can address each of these weaknesses. We report how novel co-catalyst morphologies can greatly increase efficiency for the water reduction half-reaction. We also report photostability for CdSe@CdS under high intensity 455nm light (a wavelength at which photocatalytic water splitting by CdSe@CdS is possible) by growing metal oxide co-catalysts on the surface of our rods.

Single crystals of Ln(NO3)3·Bpy2 where Ln = Eu, Gd, Nd, Tm, Er, La and Yb were fabricated and characterized. Materials have good optical quality, can be excited at UV or the rare earth ion transitions, demonstrate efficient luminescence and are suitable for thin film fabrication. Fabrication approaches and possible applications are discussed.

In this study, we provide a novel approach to the epitaxial integration of TiO2 with Si(100) and investigate the defect mediated ferromagnetism in TiO2 structure. Epitaxial TiO2 thin films were grown on a TiN/Si(100) epitaxial heterostructure through oxidation of TiN where a single crystalline rutile-TiO2 (r-TiO2) with a [110] out-of-plane orientation was obtained. The epitaxial relationship is determined to be TiO2(1 $\bar 1$ 0)||TiN(100) and TiO2(110)||TiN(110). We rationalized this epitaxy using the domain matching epitaxy paradigm. First TiN is grown epitaxially on Si(100). Subsequently, TiN/Si(100) samples are oxidized to create r-TiO2/TiN/Si(100) epitaxial heterostructures. The details of the mechanism behind the oxidation of single crystalline TiN to TiO2 was investigated using atomic scale high resolution electron microscopy techniques. Defects introduced to the heterostructure during oxidation caused ferromagnetism in TiO2 thin film which is reversible and can be tuned by controlling oxygen partial pressure. The source of magnetization is correlated with the presence of oxygen vacancy leading to introduction of two localized states; hybrid and polaron among neighboring Ti atoms, and titanium vacancy providing four holes to form molecular oxygen. We present structure property correlations and its impact on the next generation solid state devices.

Quantum dots have been applied in sensing with success, but their use in environmental applications has been questioned due to their heavy metal content. Carbon dots are fluorescent nanoparticles that offer a promising alternative to quantum dots for sensing, due to their low cost, benign fabrication process and negligible environmental impact. Fluorescence sensors are specially suited for detection of nitroaromatic compounds such as 2,4,6-trinitrotoluene (TNT) and 2,4-dinitrotoluene (DNT), since they can quench the emission of excited species. When combined to Molecularly Imprinted Polymers (MIPs), the sensors become specific to the imprinted target molecules. Amino-functionalized carbon dots (CDs) with high photoluminescence were fabricated. The CDs were characterized with respect to their surface charge, surface chemistry, particle size distribution, and photoluminescence properties (PL). A molecularly imprinted polymer with template of DNT was combined with fluorescent carbon dots via a simple covalent reaction. The ability of aqueous DNT to quench amino CDs fluorescence was tested for concentrations in the range of 1mM to 50 mM. It can be concluded that the amino carbon dots can be used in fluorescent-labeled MIP systems and that they provide a feasible method for the detection of DNT, and potentially other nitroaromatic compounds, in environmental water samples.

Carbonate intercalated Mg-Al layered double hydroxides (Mg-Al-CO3-LDH) were successfully produced by mechanical alloying process using different starting raw chemicals. Two distinct chemical reactions were activated at different milling times. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Results revealed that the structural characteristics of Mg-Al-CO3-LDH such as lattice parameters, unit cell volume, and the interlayer spacing were affected strongly by milling time. Based on the XRD data, the formation rate of pure Hydrotalcite (HT) was strongly influenced by the chemical composition of raw materials. Electron microscopic observation displayed that the final product had a platelet-like structure with an average particle size of 20-100 nm. Therefore, the synthesis of Mg-Al-CO3-LDH via a cost-effective solid-state method owing to simplicity and reproducibility can be a promising candidate especially for use in biomaterials and catalyst industries.

For practical use of Resistive Random Access Memory (ReRAM), understanding resistive switching mechanism in transition metal oxides (TMO) is important. Some papers predict its mechanism by using first principles calculation; for example, TMO become conductive by introducing oxygen vacancy in bulk single crystalline TMO. However, most of ReRAM samples have polycrystalline structures. In this paper, we introduced a periodic slab model to depict grain boundary and calculated the surface energy and density of states for surfaces of NiO with various orientations using first-principles calculation to consider the effect of grain boundaries for resistive switching mechanisms of ReRAM. As a results, vacancies can be formed on the side surface of grain more easily than in grain. Moreover, we showed that surface conductivity depends on surface orientation of NiO and the orientation of side surface of grain can change easily by introduction of vacancies, which is the switching mechanism of NiO-ReRAM

The photosynthetic reaction center (RC) from the purple Rhodobacter (R.)sphaeroides bacterium is a protein with unique photoconversioncapability that can be exploited in hybrid systems for energy conversion. Wehave developed a tailored aryleneethynylene organic fluorophore (AE750) actingas efficient light harvesting antenna and successfully bioconjugated it to thephotosynthetic RC. We have also demonstrated that, under suitable conditions,the biohybrid AE750-RC system can outperform the energy photoconversion abilityof the native protein.

Graphene quantum dots (GQDs) of different sizes were synthesized by the top-down approach, using charcoal as the precursor material. Size and absorption characteristics of synthesized GQDs were analyzed using Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Photoluminescence Spectroscopy (PL), and UV-vis Spectroscopy. The results showed that GQDs with an average height of 8.5 nm, synthesized at a relatively lower temperature of 85°C, exhibited higher UV and visible light absorption. GQD concentration was varied to form 0.5, 1, 2.5, and 5 wt.% GQD-titania (TiO2) nano composites. Surface morphology of the composite was examined using Scanning Electron Microscopy (SEM). Photocatalytic activity of the samples was assessed from methylene blue dye degradation in UV irradiation at 340nm. A distinguishable trend for pure TiO2 and composites at various concentrations were observed.

Controlling the bending properties of ionic polymer-metal composites may immediately affect their implementation in robotics and medicine. In the present work, we propose a direct patterning method for the ionic polymer Nafion using conventional electron-beam writing. In a proof-of-concept study, we show that patterns of arbitrary geometry and sizes between 1 µm and 50 µm can be engraved into the polymer surface without using resists. Pattern depth can be deliberately controlled by adjusting the exposure dose. The patterns were stable even after prolonged immersion in ionic solution. The presented technique therefore opens up the possibility to create unique electrode geometries and to investigate independently the effect of pattern size, density, depth as well as geometry on ionic polymer-metal composite bending.

The unique and remarkable properties of graphene can be exploited as the basis toa wide range of applications. However, in spite of years of investigations thereare some important graphene properties that are not still fully understood, asfor example, its wettability. There are controversial reported results whethergraphene is really hydrophobic or hydrophilic. In order to address this problemwe have carried out classical molecular dynamics simulations of waternanodroplets shot against graphene surface. Our results show that the contactangle values between the nanodroplets and graphene surfaces depend on theinitial droplet velocity value and these angles can change from 86°(hydrophobic) to 35° (hydrophilic). Our preliminary results indicatethat the graphene wettability can be dependent on spreading liquid dynamics andwhich can explain some of the apparent inconsistencies reported in theliterature.

Aluminum alloy 6082 (AA6082) should be a suitable material for use as casings in offshore based sensors due to its mechanical strength and corrosion resistance. However, there is concern with this materials remaining strength after a fire. This paper will discuss the room temperature creep behavior of AA6082 samples after thermal aging at various temperatures. Samples were aged at a constant temperature in the range 373 K to 423 K and for durations ranging from 4 hr to 24 hr. The creep behavior was investigated using loads slightly exceeding the yield strength of aged samples. We propose an empirical model to relate steady state creep rate at room temperature with aging temperature and time. Such empirical relationship can potentially be used in deciding whether AA6082 casings can still be used to carry loads after exposure to elevated temperatures such as platform fires.

An integrated experimental – simulation – control theory approach designed to enable adaptive control of microstructural evolution in polycrystalline metals is described. A micro-heater array, containing ten addressable channels, is used to create desired temperature profiles across thin polycrystalline films in situ to a scanning electron microscope (SEM). The goal is that on heating with controlled temperature profiles, the evolution of grain growth within the film can be continuously monitored and compared to Monte Carlo simulations of trajectories towards a desired microstructure. Feed-forward and feedback control strategies are then used to guide the microstructure along the desired trajectory.

The luminescence of Tb-doped a-SiC:H thin films with different Tb concentrations under sub-bandgap photon excitation was investigated. Two independent processes were identified. The annealing induced activation of the Tb3+ and the inhibition of host-mediated non-radiative recombination paths. The integrated emission intensity is described by a rate equation model, considering these two. In this study, the luminescence enhancement with increasing annealing temperature is shown. The optimal Tb concentration and annealing temperature for the highest Tb-related light emission intensity is determined. Finally, a parameter proportional to the number of optically active ions is found through the aforementioned model.